The sealing of integrated circuit packages to prevent contamination and deterioration from the environment is critical in the field of semiconductor packaging. To this end many components are often sealed from the atmosphere by fusing a glass layer over the components or in the alternative by soldering a metal lid over a substrate on which a semiconductor chip has been mounted. Such methods of sealing unfortunately subject the component to be protected to considerable thermal stress during the process of fusing or soldering and do not allow non-destructive reopening of the package for rework.
U.S. Pat. No. 4,126,758 discloses my earlier method and apparatus for sealing electrical components by positioning over an electrical component a heat-recoverable sealing lid. Upon recovery the lid 14 expands to seal against an upstanding ring 18 that is attached to the package. It can be appreciated that such a design requires precision tolerances between a heat-recoverable lid and the ring to effect the seal and that the greater the forces generated by the heat-recoverable lid, the greater the chances that the lid will destroy the interface between the ring and the substrate of the package especially in thermal cycling over time which occurs each time the device is turned on and off.
It would therefore be highly desirable to have an integrated circuit package that could utilize the benefits of a heat-recoverable material such as a shape-memory alloy to effect an environmental seal without requiring precise tolerances and without jeopardizing the integrity of the package due to the sealing forces generated by the heat-recoverable member. The instant invention provides such an improved package and in certain configurations allows simple non-destructive re-entry to the package for rework and subsequent resealing.